1. Field of the Invention
The present invention pertains to vehicle headlights whose light beam patterns can be adjusted by changing the shape of lenses that modify the headlight beams.
2. Description of Prior Art
Heretofore it has been the practice to adjust the distribution of the illumination from a vehicle's headlights by altering the position or distance between the glower and modifier or the glower and reflector. In the dual filament high beam-low beam headlight used on highway vehicles, the headlight actually contains two glowers and two electrical circuits which are energized alternately. The dual filament headlight has only two settings; high beam, when there is no oncoming traffic; and low beam when the high beam would cause too much glare for the driver of an oncoming vehicle, too much glare in the rear view mirrors of a vehicle ahead, or, in the case of fog or falling snow, too much reflective glare for the vehicle operator. A way that is currently used to achieve some degree of versatility in illuminating a vehicle's path is by using additional lights and wiring systems such as automobile quad headlights, and fog lights.
Around 1980, Halogen and other arc discharge glowers started to be used on car headlights in the United States. These types of light sources produce approximately five times the candlepower that regular incandescent headlights do. While they increase visibility somewhat, with the limited amount of adjustment that can be made to the beam direction and shape, their full potential to illuminate cannot be realized and, conversely, these powerful lights would make a more versatile system of adjustment an even greater benefit to driving safety.
There have been patents issued for variable shaped (sometimes referred to as variable focus) lenses over the years. Almost all of the objects of these patents require a relatively high degree of precision. Examples are lenses for image formers such as eyeglasses and cameras, or for concentrating light on extremely small targets in laser applications. Such applications have not had commercial success since ground or moulded lenses of glass or plastic achieve a higher degree of precision than the adjustable shape lens is capable of achieving. However the shape of a headlight beam is much less precise. Even the narrowest, most concentrated headlight beam is designed to be wider as it projects forward than it is at the aperture of the headlight, and sufficiently accurate adjustment of the light beam for height and shape could be achieved with variably shaped lenses.
Italy patent 442466 (Rappazzo, 23 Nov. 1948) shows a vehicle headlight with an variably shaped lens. In the Rappazzo patent two transparent walls forming a chamber that is filled with a transparent liquid comprise the lens through which light from the glower and reflector pass. The method of adjusting the shape of the lens is by adding or removing the liquid to the chamber so that the chamber expands or contracts. The operation of this device is similar to the operation of the lens in the preferred embodiment of my invention.
Such a lens containing a liquid would offer significant advantages over current types of headlights; however, a major problem of liquid lenses in moving vehicles is the shifting of the liquid and, therefore, the distortion of the lens to an unacceptable degree whenever the vehicle changes speed or direction. In the case of a moving highway vehicle, in addition to changes of speed, changes of direction are continuously caused by vibration and turning.